Extreme ultraviolet mask absorber materials

ABSTRACT

Extreme ultraviolet (EUV) mask blanks, methods for their manufacture and production systems therefor are disclosed. The EUV mask blanks comprise a substrate; a multilayer stack of reflective layers on the substrate; a capping layer on the multilayer stack of reflecting layers; and an absorber layer on the capping layer, the absorber layer comprising an alloy of molybdenum (Mo) and antimony (Sb).

TECHNICAL FIELD

The present disclosure relates generally to extreme ultravioletlithography, and more particularly extreme ultraviolet mask blanks withan alloy absorber and methods of manufacture.

BACKGROUND

Extreme ultraviolet (EUV) lithography, also known as soft x-rayprojection lithography, is used for the manufacture of 0.0135 micron andsmaller minimum feature size semiconductor devices. However, extremeultraviolet light, which is generally in the 5 to 100 nanometerwavelength range, is strongly absorbed in virtually all materials. Forthat reason, extreme ultraviolet systems work by reflection rather thanby transmission of light. Through the use of a series of mirrors, orlens elements, and a reflective element, or mask blank, coated with anon-reflective absorber mask pattern, the patterned actinic light isreflected onto a resist-coated semiconductor substrate.

The lens elements and mask blanks of extreme ultraviolet lithographysystems are coated with reflective multilayer coatings of materials suchas molybdenum (Mo) and silicon (Si). Reflection values of approximately65% per lens element, or mask blank, have been obtained by usingsubstrates that are coated with multilayer coatings that stronglyreflect light within an extremely narrow ultraviolet bandpass, forexample, 12.5 to 14.5 nanometer bandpass for 13.5 nanometer ultravioletlight.

FIG. 1 shows a conventional EUV reflective mask 10, which is formed froman EUV mask blank, which includes a reflective multilayer stack 12 on asubstrate 14, which reflects EUV radiation at unmasked portions by Bragginterference. Masked (non-reflective) areas 16 of the conventional EUVreflective mask 10 are formed by etching buffer layer 18 and absorbinglayer 20. The absorbing layer typically has a thickness in a range of 51nm to 77 nm. A capping layer 22 is formed over the reflective multilayerstack 12 and protects the reflective multilayer stack 12 during theetching process. As will be discussed further below, EUV mask blanks aremade on a low thermal expansion material substrate coated withmultilayers, a capping layer and an absorbing layer, which is thenetched to provide the masked (non-reflective) areas 16 and reflectiveareas 24.

The International Technology Roadmap for Semiconductors (ITRS) specifiesa node's overlay requirement as some percentage of a technology'sminimum half-pitch feature size. Due to the impact on image placementand overlay errors inherent in all reflective lithography systems, EUVreflective masks will need to adhere to more precise flatnessspecifications for future production. Additionally, EUV blanks have avery low tolerance to defects on the working area of the blank.Furthermore, while the absorbing layer's role is to absorb light, thereis also a phase shift effect due to the difference between the absorberlayer's index of refraction and vacuum's index of refraction (n=1), andthis phase shift that accounts for the 3D mask effects. There is a needto provide EUV mask blanks having a thinner absorber to mitigate 3D maskeffects.

SUMMARY

One or more embodiments of the disclosure are directed to a method ofmanufacturing an extreme ultraviolet (EUV) mask blank comprising formingon a substrate a multilayer stack which reflects EUV radiation, themultilayer stack comprising a plurality of reflective layer pairs;forming a capping layer on the multilayer stack; and forming an absorberlayer on the capping layer, the absorber layer comprising an alloy ofmolybdenum (Mo) and antimony (Sb).

Additional embodiments of the disclosure are directed to an EUV maskblank comprising a substrate; a multilayer stack which reflects EUVradiation, the multilayer stack comprising a plurality of reflectivelayer pairs; a capping layer on the multilayer stack of reflectinglayers; and an absorber layer on the capping layer, the absorber layercomprising an alloy of molybdenum (Mo) and antimony (Sb).

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 schematically illustrates a background art EUV reflective maskemploying a conventional absorber;

FIG. 2 schematically illustrates an embodiment of an extreme ultravioletlithography system;

FIG. 3 illustrates an embodiment of an extreme ultraviolet reflectiveelement production system;

FIG. 4 illustrates an embodiment of an extreme ultraviolet reflectiveelement such as an EUV mask blank;

FIG. 5 illustrates an embodiment of an extreme ultraviolet reflectiveelement such as an EUV mask blank; and

FIG. 6 illustrates an embodiment of a multi-cathode physical depositionchamber.

DETAILED DESCRIPTION

Before describing several exemplary embodiments of the disclosure, it isto be understood that the disclosure is not limited to the details ofconstruction or process steps set forth in the following description.The disclosure is capable of other embodiments and of being practiced orbeing carried out in various ways.

The term “horizontal” as used herein is defined as a plane parallel tothe plane or surface of a mask blank, regardless of its orientation. Theterm “vertical” refers to a direction perpendicular to the horizontal asjust defined. Terms, such as “above”, “below”, “bottom”, “top”, “side”(as in “sidewall”), “higher”, “lower”, “upper”, “over”, and “under”, aredefined with respect to the horizontal plane, as shown in the figures.

The term “on” indicates that there is direct contact between elements.The term “directly on” indicates that there is direct contact betweenelements with no intervening elements.

Those skilled in the art will understand that the use of ordinals suchas “first” and “second” to describe process regions do not imply aspecific location within the processing chamber, or order of exposurewithin the processing chamber.

As used in this specification and the appended claims, the term“substrate” refers to a surface, or portion of a surface, upon which aprocess acts. It will also be understood by those skilled in the artthat reference to a substrate refers to only a portion of the substrate,unless the context clearly indicates otherwise. Additionally, referenceto depositing on a substrate means both a bare substrate and a substratewith one or more films or features deposited or formed thereon.

Referring now to FIG. 2, an exemplary embodiment of an extremeultraviolet lithography system 100 is shown. The extreme ultravioletlithography system 100 includes an extreme ultraviolet light source 102for producing extreme ultraviolet light 112, a set of reflectiveelements, and a target wafer 110. The reflective elements include acondenser 104, a EUV reflective mask 106, an optical reduction assembly108, a mask blank, a mirror, or a combination thereof.

The extreme ultraviolet light source 102 generates the extremeultraviolet light 112. The extreme ultraviolet light 112 iselectromagnetic radiation having a wavelength in a range of 5 to 50nanometers (nm). For example, the extreme ultraviolet light source 102includes a laser, a laser produced plasma, a discharge produced plasma,a free-electron laser, synchrotron radiation, or a combination thereof.

The extreme ultraviolet light source 102 generates the extremeultraviolet light 112 having a variety of characteristics. The extremeultraviolet light source 102 produces broadband extreme ultravioletradiation over a range of wavelengths. For example, the extremeultraviolet light source 102 generates the extreme ultraviolet light 112having wavelengths ranging from 5 to 50 nm. In one or more embodiments,the extreme ultraviolet light source 102 produces the extremeultraviolet light 112 having a narrow bandwidth. For example, theextreme ultraviolet light source 102 generates the extreme ultravioletlight 112 at 13.5 nm. The center of the wavelength peak is 13.5 nm.

The condenser 104 is an optical unit for reflecting and focusing theextreme ultraviolet light 112. The condenser 104 reflects andconcentrates the extreme ultraviolet light 112 from the extremeultraviolet light source 102 to illuminate the EUV reflective mask 106.

Although the condenser 104 is shown as a single element, it isunderstood that the condenser 104 in some embodiments includes one ormore reflective elements such as concave mirrors, convex mirrors, flatmirrors, or a combination thereof, for reflecting and concentrating theextreme ultraviolet light 112. For example, the condenser 104 in someembodiments is a single concave mirror or an optical assembly havingconvex, concave, and flat optical elements.

The EUV reflective mask 106 is an extreme ultraviolet reflective elementhaving a mask pattern 114. The EUV reflective mask 106 creates alithographic pattern to form a circuitry layout to be formed on thetarget wafer 110. The EUV reflective mask 106 reflects the extremeultraviolet light 112. The mask pattern 114 defines a portion of thecircuitry layout.

The optical reduction assembly 108 is an optical unit for reducing theimage of the mask pattern 114. The reflection of the extreme ultravioletlight 112 from the EUV reflective mask 106 is reduced by the opticalreduction assembly 108 and reflected on to the target wafer 110. Theoptical reduction assembly 108 in some embodiments includes mirrors andother optical elements to reduce the size of the image of the maskpattern 114. For example, the optical reduction assembly 108 in someembodiments includes concave mirrors for reflecting and focusing theextreme ultraviolet light 112.

The optical reduction assembly 108 reduces the size of the image of themask pattern 114 on the target wafer 110. For example, the mask pattern114 in some embodiments is imaged at a 4:1 ratio by the opticalreduction assembly 108 on the target wafer 110 to form the circuitryrepresented by the mask pattern 114 on the target wafer 110. The extremeultraviolet light 112 in some embodiments scans the EUV reflective mask106 synchronously with the target wafer 110 to form the mask pattern 114on the target wafer 110.

Referring now to FIG. 3, an embodiment of an extreme ultravioletreflective element production system 200 is shown. The extremeultraviolet reflective element includes a EUV mask blank 204, an extremeultraviolet mirror 205, or other reflective element such as an EUVreflective mask 106.

The extreme ultraviolet reflective element production system 200 in someembodiments produces mask blanks, mirrors, or other elements thatreflect the extreme ultraviolet light 112 of FIG. 2. The extremeultraviolet reflective element production system 200 fabricates thereflective elements by applying thin coatings to source substrates 203.

The EUV mask blank 204 is a multilayered structure for forming the EUVreflective mask 106 of FIG. 2. The EUV mask blank 204 in someembodiments is formed using semiconductor fabrication techniques. TheEUV reflective mask 106 in some embodiments has the mask pattern 114 ofFIG. 2 formed on the EUV mask blank 204 by etching and other processes.

The extreme ultraviolet mirror 205 is a multilayered structurereflective in a range of extreme ultraviolet light 112. The extremeultraviolet mirror 205 in some embodiments is formed using semiconductorfabrication techniques. The EUV mask blank 204 and the extremeultraviolet mirror 205 in some embodiments are similar structures withrespect to the layers formed on each element, however, the extremeultraviolet mirror 205 does not have the mask pattern 114.

The reflective elements are efficient reflectors of the extremeultraviolet light 112. In an embodiment, the EUV mask blank 204 and theextreme ultraviolet mirror 205 has an extreme ultraviolet reflectivityof greater than 60%. The reflective elements are efficient if theyreflect more than 60% of the extreme ultraviolet light 112.

The extreme ultraviolet reflective element production system 200includes a wafer loading and carrier handling system 202 into which thesource substrates 203 are loaded and from which the reflective elementsare unloaded. An atmospheric handling system 206 provides access to awafer handling vacuum chamber 208. The wafer loading and carrierhandling system 202 in some embodiments includes substrate transportboxes, loadlocks, and other components to transfer a substrate fromatmosphere to vacuum inside the system. Because the EUV mask blank 204is used to form devices at a very small scale, the source substrates 203and the EUV mask blank 204 are processed in a vacuum system to preventcontamination and other defects.

The wafer handling vacuum chamber 208 in some embodiments contains twovacuum chambers, a first vacuum chamber 210 and a second vacuum chamber212. The first vacuum chamber 210 includes a first wafer handling system214 and the second vacuum chamber 212 includes a second wafer handlingsystem 216. Although the wafer handling vacuum chamber 208 is describedwith two vacuum chambers, it is understood that the system in someembodiments has any number of vacuum chambers.

The wafer handling vacuum chamber 208 in some embodiments has aplurality of ports around its periphery for attachment of various othersystems. The first vacuum chamber 210 has a degas system 218, a firstphysical vapor deposition system 220, a second physical vapor depositionsystem 222, and a pre-clean system 224. The degas system 218 is forthermally desorbing moisture from the substrates. The pre-clean system224 is for cleaning the surfaces of the wafers, mask blanks, mirrors, orother optical components.

The physical vapor deposition systems, such as the first physical vapordeposition system 220 and the second physical vapor deposition system222, in some embodiments are used to form thin films of conductivematerials on the source substrates 203. For example, the physical vapordeposition systems in some embodiments includes vacuum deposition systemsuch as magnetron sputtering systems, ion sputtering systems, pulsedlaser deposition, cathode arc deposition, or a combination thereof. Thephysical vapor deposition systems, such as the magnetron sputteringsystem, form thin layers on the source substrates 203 including thelayers of silicon, metals, alloys, compounds, or a combination thereof.

The physical vapor deposition system forms reflective layers, cappinglayers, and absorber layers. For example, the physical vapor depositionsystems in some embodiments forms layers of silicon, molybdenum,ruthenium, tantalum, antimony, titanium oxide, titanium dioxide,ruthenium oxide, niobium oxide, iridium, iridium oxide, rutheniumtungsten, ruthenium molybdenum, ruthenium niobium, chromium, platinum,iron, copper, boron, nickel, bismuth, tellurium, hafnium, tantalum,nitrides, compounds, or a combination thereof. Although some compoundsare described as an oxide, it is understood that the compounds in someembodiments include oxides, dioxides, atomic mixtures having oxygen (O)atoms, or a combination thereof.

The second vacuum chamber 212 has a first multi-cathode source 226, achemical vapor deposition system 228, a cure chamber 230, and anultra-smooth deposition chamber 232 connected to it. For example, thechemical vapor deposition system 228 in some embodiments includes aflowable chemical vapor deposition system (FCVD), a plasma assistedchemical vapor deposition system (CVD), an aerosol assisted CVD system,a hot filament CVD system, or a similar system. In another example, thechemical vapor deposition system 228, the cure chamber 230, and theultra-smooth deposition chamber 232 in some embodiments are in aseparate system from the extreme ultraviolet reflective elementproduction system 200.

The chemical vapor deposition system 228 in some embodiments forms thinfilms of material on the source substrates 203. For example, thechemical vapor deposition system 228 in some embodiments is used to formlayers of materials on the source substrates 203 includingmono-crystalline layers, polycrystalline layers, amorphous layers,epitaxial layers, or a combination thereof. The chemical vapordeposition system 228 in some embodiments forms layers of silicon,silicon oxides, silicon oxycarbide, tantalum, tellurium, antimony,platinum, iridium, hafnium, iron, copper, boron, nickel, tungsten,bismuth silicon carbide, silicon nitride, titanium nitride, metals,alloys, and other materials suitable for chemical vapor deposition. Forexample, the chemical vapor deposition system 228 in some embodimentsforms planarization layers.

The first wafer handling system 214 is capable of moving the sourcesubstrates 203 between the atmospheric handling system 206 and thevarious systems around the periphery of the first vacuum chamber 210 ina continuous vacuum. The second wafer handling system 216 is capable ofmoving the source substrates 203 around the second vacuum chamber 212while maintaining the source substrates 203 in a continuous vacuum. Theextreme ultraviolet reflective element production system 200 in someembodiments transfers the source substrates 203 and the EUV mask blank204 between the first wafer handling system 214, the second waferhandling system 216 in a continuous vacuum.

Referring now to FIG. 4, an embodiment of an extreme ultravioletreflective element 302 is shown. In one or more embodiments, the extremeultraviolet reflective element 302 is the EUV mask blank 204 of FIG. 3or the extreme ultraviolet mirror 205 of FIG. 3. The EUV mask blank 204and the extreme ultraviolet mirror 205 are structures for reflecting theextreme ultraviolet light 112 of FIG. 2. The EUV mask blank 204 in someembodiments is used to form the EUV reflective mask 106 shown in FIG. 2.

The extreme ultraviolet reflective element 302 includes a substrate 304,a multilayer stack 306 of reflective layers, and a capping layer 308. Inone or more embodiments, the extreme ultraviolet mirror 205 is used toform reflecting structures for use in the condenser 104 of FIG. 2 or theoptical reduction assembly 108 of FIG. 2.

The extreme ultraviolet reflective element 302, which in someembodiments is a EUV mask blank 204, includes the substrate 304, themultilayer stack 306 of reflective layers, the capping layer 308, and anabsorber layer 310. The extreme ultraviolet reflective element 302 insome embodiments is a EUV mask blank 204, which is used to form the EUVreflective mask 106 of FIG. 2 by patterning the absorber layer 310 withthe layout of the circuitry required.

In the following sections, the term for the EUV mask blank 204 is usedinterchangeably with the term of the extreme ultraviolet mirror 205 forsimplicity. In one or more embodiments, the EUV mask blank 204 includesthe components of the extreme ultraviolet mirror 205 with the absorberlayer 310 added in addition to form the mask pattern 114 of FIG. 2.

The EUV mask blank 204 is an optically flat structure used for formingthe EUV reflective mask 106 having the mask pattern 114. In one or moreembodiments, the reflective surface of the EUV mask blank 204 forms aflat focal plane for reflecting the incident light, such as the extremeultraviolet light 112 of FIG. 2.

The substrate 304 is an element for providing structural support to theextreme ultraviolet reflective element 302. In one or more embodiments,the substrate 304 is made from a material having a low coefficient ofthermal expansion (CTE) to provide stability during temperature changes.In one or more embodiments, the substrate 304 has properties such asstability against mechanical cycling, thermal cycling, crystalformation, or a combination thereof. The substrate 304 according to oneor more embodiments is formed from a material such as silicon (Si),glass, oxides, ceramics, glass ceramics, or a combination thereof.

The multilayer stack 306 is a structure that is reflective to theextreme ultraviolet light 112. The multilayer stack 306 includesalternating reflective layers of a first reflective layer 312 and asecond reflective layer 314.

The first reflective layer 312 and the second reflective layer 314 forma reflective pair 316 of FIG. 4. In a non-limiting embodiment, themultilayer stack 306 includes a range of 20-60 of the reflective pairs316 for a total of up to 120 reflective layers.

The first reflective layer 312 and the second reflective layer 314 insome embodiments are formed from a variety of materials. In anembodiment, the first reflective layer 312 and the second reflectivelayer 314 are formed from silicon (Si) and molybdenum (Mo),respectively. Although the layers are shown as silicon (Si) andmolybdenum (Mo), it is understood that the alternating layers in someembodiments are formed from other materials or have other internalstructures.

The first reflective layer 312 and the second reflective layer 314 insome embodiments have a variety of structures. In an embodiment, boththe first reflective layer 312 and the second reflective layer 314 areformed with a single layer, multiple layers, a divided layer structure,non-uniform structures, or a combination thereof.

Because most materials absorb light at extreme ultraviolet wavelengths,the optical elements used are reflective instead of the transmissive asused in other lithography systems. The multilayer stack 306 forms areflective structure by having alternating thin layers of materials withdifferent optical properties to create a Bragg reflector or mirror.

In an embodiment, each of the alternating layers has dissimilar opticalconstants for the extreme ultraviolet light 112. The alternating layersprovide a resonant reflectivity when the period of the thickness of thealternating layers is one half the wavelength of the extreme ultravioletlight 112. In an embodiment, for the extreme ultraviolet light 112 at awavelength of 13 nm, the alternating layers are about 6.5 nm thick. Itis understood that the sizes and dimensions provided are within normalengineering tolerances for typical elements.

The multilayer stack 306 in some embodiments is formed in a variety ofways. In an embodiment, the first reflective layer 312 and the secondreflective layer 314 are formed with magnetron sputtering, ionsputtering systems, pulsed laser deposition, cathode arc deposition, ora combination thereof.

In an illustrative embodiment, the multilayer stack 306 is formed usinga physical vapor deposition technique, such as magnetron sputtering. Inan embodiment, the first reflective layer 312 and the second reflectivelayer 314 of the multilayer stack 306 have the characteristics of beingformed by the magnetron sputtering technique including precisethickness, low roughness, and clean interfaces between the layers. In anembodiment, the first reflective layer 312 and the second reflectivelayer 314 of the multilayer stack 306 have the characteristics of beingformed by the physical vapor deposition including precise thickness, lowroughness, and clean interfaces between the layers.

The physical dimensions of the layers of the multilayer stack 306 formedusing the physical vapor deposition technique in some embodiments areprecisely controlled to increase reflectivity. In an embodiment, thefirst reflective layer 312, such as a layer of silicon (Si), has athickness of 4.1 nm. The second reflective layer 314, such as a layer ofmolybdenum (Mo), has a thickness of 2.8 nm. The thickness of the layersdictates the peak reflectivity wavelength of the extreme ultravioletreflective element. If the thickness of the layers is incorrect, thereflectivity at the desired wavelength 13.5 nm in some embodiments isreduced.

In an embodiment, the multilayer stack 306 has a reflectivity of greaterthan 60%. In an embodiment, the multilayer stack 306 formed usingphysical vapor deposition has a reflectivity in a range of 66%-67%. Inone or more embodiments, forming the capping layer 308 over themultilayer stack 306 formed with harder materials improves reflectivity.In some embodiments, reflectivity greater than 70% is achieved using lowroughness layers, clean interfaces between layers, improved layermaterials, or a combination thereof.

In one or more embodiments, the capping layer 308 is a protective layerallowing the transmission of the extreme ultraviolet light 112. In anembodiment, the capping layer 308 is formed directly on the multilayerstack 306. In one or more embodiments, the capping layer 308 protectsthe multilayer stack 306 from contaminants and mechanical damage. In oneembodiment, the multilayer stack 306 is sensitive to contamination byoxygen (O), tantalum (Ta), hydrotantalums, or a combination thereof. Thecapping layer 308 according to an embodiment interacts with thecontaminants to neutralize them.

In one or more embodiments, the capping layer 308 is an opticallyuniform structure that is transparent to the extreme ultraviolet light112. The extreme ultraviolet light 112 passes through the capping layer308 to reflect off of the multilayer stack 306. In one or moreembodiments, the capping layer 308 has a total reflectivity loss of 1%to 2%. In one or more embodiments, each of the different materials has adifferent reflectivity loss depending on thickness, but all of them willbe in a range of 1% to 2%.

In one or more embodiments, the capping layer 308 has a smooth surface.For example, the surface of the capping layer 308 in some embodimentshas a roughness of less than 0.2 nm RMS (root mean square measure). Inanother example, the surface of the capping layer 308 has a roughness of0.08 nm RMS for a length in a range of 1/100 nm and 1/1 μm. The RMSroughness will vary depending on the range it is measured over. For thespecific range of 100 nm to 1 micron that roughness is 0.08 nm or less.Over a larger range the roughness will be higher.

The capping layer 308 in some embodiments is formed in a variety ofmethods. In an embodiment, the capping layer 308 is formed on ordirectly on the multilayer stack 306 with magnetron sputtering, ionsputtering systems, ion beam deposition, electron beam evaporation,radio frequency (RF) sputtering, atomic layer deposition (ALD), pulsedlaser deposition, cathode arc deposition, or a combination thereof. Inone or more embodiments, the capping layer 308 has the physicalcharacteristics of being formed by the magnetron sputtering techniqueincluding precise thickness, low roughness, and clean interfaces betweenthe layers. In an embodiment, the capping layer 308 has the physicalcharacteristics of being formed by the physical vapor depositionincluding precise thickness, low roughness, and clean interfaces betweenthe layers.

In one or more embodiments, the capping layer 308 is formed from avariety of materials having a hardness sufficient to resist erosionduring cleaning. In one embodiment, ruthenium (Ru) is used as a cappinglayer material because it is a good etch stop and is relatively inertunder the operating conditions. However, it is understood that othermaterials in some embodiments are used to form the capping layer 308. Inspecific embodiments, the capping layer 308 has a thickness in a rangeof 2.5 and 5.0 nm.

In one or more embodiments, the absorber layer 310 is a layer thatabsorbs the extreme ultraviolet light 112. In an embodiment, theabsorber layer 310 is used to form the pattern on the EUV reflectivemask 106 by providing areas that do not reflect the extreme ultravioletlight 112. The absorber layer 310, according to one or more embodiments,comprises a material having a high absorption coefficient for aparticular frequency of the extreme ultraviolet light 112, such as about13.5 nm. In an embodiment, the absorber layer 310 is formed directly onthe capping layer 308, and the absorber layer 310 is etched using aphotolithography process to form the pattern of the EUV reflective mask106.

According to one or more embodiments, the extreme ultraviolet reflectiveelement 302, such as the extreme ultraviolet mirror 205, is formed withthe substrate 304, the multilayer stack 306, and the capping layer 308.The extreme ultraviolet mirror 205 has an optically flat surface and insome embodiments efficiently and uniformly reflects the extremeultraviolet light 112.

According to one or more embodiments, the extreme ultraviolet reflectiveelement 302, such as the EUV mask blank 204, is formed with thesubstrate 304, the multilayer stack 306, the capping layer 308, and theabsorber layer 310. The mask blank 204 has an optically flat surface andin some embodiments efficiently and uniformly reflects the extremeultraviolet light 112. In an embodiment, the mask pattern 114 is formedwith the absorber layer 310 of the EUV mask blank 204.

According to one or more embodiments, forming the absorber layer 310over the capping layer 308 increases reliability of the EUV reflectivemask 106. The capping layer 308 acts as an etch stop layer for theabsorber layer 310. When the mask pattern 114 of FIG. 2 is etched intothe absorber layer 310, the capping layer 308 beneath the absorber layer310 stops the etching action to protect the multilayer stack 306. In oneor more embodiments, the absorber layer 310 is etch selective to thecapping layer 308. In some embodiments, the capping layer 308 comprisesruthenium (Ru), and the absorber layer 310 is etch selective toruthenium (Ru).

In an embodiment, the absorber layer 310 comprises an alloy ofmolybdenum (Mo) and antimony (Sb). In some embodiments the absorber hasa thickness of less than about 100 nm. In some embodiments, the absorberlayer has a thickness of less than about 65 nm, including less thanabout 60 nm, less than about 55 nm, less than about 50 nm, less thanabout 45 nm, less than about 40 nm, or less than about 35 nm. In otherembodiments, the absorber layer 310 has a thickness in a range of fromabout 0.5 nm to about 100 nm, from about 0.5 nm to about 85 nm, fromabout 0.5 nm to about 75 nm, from about 0.5 nm to about 65 nm, includinga range of from about 1 nm to about 100 nm, from about 1 nm to about 90nm, from about 1 nm to about 80 nm, from about 1 nm to about 70 nm, fromabout 1 nm to about 60 nm, 1 nm to about 55 nm, and 15 nm to about 50nm.

Simulated testing of absorbers comprising an alloy of molybdenum (Mo)and antimony (Sb) showed better lithography performance compared to atantalum nitride (TaN) absorber. The alloy absorbers described hereinshowed better Depth of Focus (DOF), Normalized Image Log-Slope (NILS)and Telecentricity error (TCE) compared to a TaN absorber. In one ormore embodiments, the alloy absorbers described herein showed phaseshift of π to 1.3π with thinner thickness than traditional EUV absorbermaterials such as TaN.

In one or more embodiments, the absorber layer comprises an alloy ofmolybdenum (Mo) and antimony (Sb), and the alloy comprises from about3.9 wt. % to about 93.8 wt. % molybdenum (Mo) and from about 6.2 wt. %to about 96.1 wt. % antimony (Sb) based upon the total weight of thealloy. In one or more embodiments, the alloy comprises from about 13.9wt. % to about 93.8 wt. % molybdenum (Mo) and from about 6.2 wt. % toabout 86.1 wt. % antimony (Sb) based upon the total weight of the alloy.In one or more embodiments, the alloy comprises from about 23.9 wt. % toabout 93.8 wt. % molybdenum (Mo) and from about 6.2 wt. % to about 76.1wt. % antimony (Sb) based upon the total weight of the alloy. In one ormore embodiments, the alloy comprises from about 33.9 wt. % to about93.8 wt. % molybdenum (Mo) and from about 6.2 wt. % to about 66.1 wt. %antimony (Sb) based upon the total weight of the alloy. In one or moreembodiments, the alloy of molybdenum (Mo) and antimony (Sb) is asingle-phase alloy.

In one or more embodiments, the alloy of molybdenum (Mo) and antimony(Sb) comprises a dopant. The dopant may be selected from one or more ofnitrogen (N) or oxygen (O). In an embodiment, the dopant comprisesoxygen (O). In an alternative embodiment, the dopant comprises nitrogen(N). In an embodiment, the dopant is present in the alloy in an amountin the range of about 0.1 wt. % to about 5 wt. %, based on the weight ofthe alloy. In other embodiments, the dopant is present in the alloy inan amount of about 0.1 wt. %, 0.2 wt. %, 0.3 wt. %, 0.4 wt. %, 0.5 wt.%, 0.6 wt. %, 0.7 wt. %. 0.8 wt. %, 0.9 wt. %, 1.0 wt. %, 1.1 wt. %, 1.2wt. %, 1.3 wt. %, 1.4 wt. %, 1.5 wt. %, 1.6 wt. %, 1.7 wt. %. 1.8 wt. %,1.9 wt. %, 2.0 wt. % 2.1 wt. %, 2.2 wt. %, 2.3 wt. %, 2.4 wt. %, 2.5 wt.%, 2.6 wt. %, 2.7 wt. %. 2.8 wt. %, 2.9 wt. %, 3.0 wt. %, 3.1 wt. %, 3.2wt. %, 3.3 wt. %, 3.4 wt. %, 3.5 wt. %, 3.6 wt. %, 3.7 wt. %. 3.8 wt. %,3.9 wt. %, 4.0 wt. %, 4.1 wt. %, 4.2 wt. %, 4.3 wt. %, 4.4 wt. %, 4.5wt. %, 4.6 wt. %, 4.7 wt. %. 4.8 wt. %, 4.9 wt. %, or 5.0 wt. %.

In one or more embodiments, the alloy of the absorber layer is aco-sputtered alloy absorber material formed in a physical depositionchamber using multiple targets comprising each of the metal componentsof the alloy, which in some embodiments provides much thinner absorberlayer thickness (e.g., less than 100 nm, less than 90 nm, less than 80nm, less than 70 nm, less than 60 nm, less than 50 nm, less than 40 nmor less than 30n m) while achieving less than 2% reflectivity andsuitable etch properties. In one or more embodiments, the alloy of theabsorber layer is co-sputtered with gases selected from one or more ofargon (Ar), oxygen (O₂), or nitrogen (N₂). In an embodiment, the alloyof the absorber layer in some embodiments is co-sputtered by a mixtureof argon and oxygen gases (Ar+O₂). In some embodiments, co-sputtering ina mixture of argon and oxygen gases (Ar+O₂) forms an oxide of molybdenum(Mo) and/or an oxide of antimony (Sb) for an alloy of molybdenum (Mo)and antimony (Sb). In other embodiments, co-sputtering by a mixture ofargon and oxygen gases (Ar+O₂) does not form an oxide of one or more thecomponents of each of the alloys disclosed herein. In an embodiment, thealloy of the absorber layer in some embodiments is co-sputtered in amixture of argon and nitrogen gases (Ar+N₂). In some embodiments,co-sputtering in a mixture of argon and nitrogen gases (Ar+N₂) forms anitride of molybdenum (Mo) and/or a nitride of antimony (Sb) for analloy of molybdenum (Mo) and antimony (Sb). In other embodiments,co-sputtering in a mixture of argon and nitrogen gases (Ar+N₂) does notform a nitride of one or more of the components of the alloys disclosedherein. In an embodiment, the alloy of the absorber layer in someembodiments is co-sputtered in a mixture of argon and oxygen andnitrogen gases (Ar+O₂+N₂). In some embodiments, co-sputtering in amixture of argon and oxygen and nitrogen gases (Ar+O₂+N₂) forms an oxideand/or nitride of molybdenum (Mo) and/or an oxide and/or nitride ofantimony (Sb) for an alloy of molybdenum (Mo) and antimony (Sb). Inother embodiments, co-sputtering in a mixture of argon and oxygen andnitrogen gases (Ar+O₂+N₂) does not form an oxide or a nitride of one ormore of the components of the alloys described herein. In an embodiment,the etch properties and/or other properties of the absorber layer insome embodiments is tailored to specification by controlling the alloypercentage(s), as discussed above. In an embodiment, the alloypercentage(s) in some embodiments is precisely controlled by operatingparameters such voltage, pressure, flow, etc., of the physical vapordeposition chamber. In an embodiment, a process gas is used to furthermodify the material properties, for example, N₂ gas is used to formnitrides of one or more components of the alloy of molybdenum (Mo) andantimony (Sb).

In one or more embodiments, as used herein “co-sputtering” means that atleast two targets, a first target comprising molybdenum (Mo) and asecond target comprising antimony (Sb) for an alloy of molybdenum (Mo)and antimony (Sb) are sputtered at the same time using one or more gasselected from argon (Ar), oxygen (O₂), or nitrogen (N₂) to deposit/forman absorber layer, the absorber layer comprising an alloy of molybdenum(Mo) and antimony (Sb).

In other embodiments, the alloy of molybdenum (Mo) and antimony (Sb) isdeposited layer by layer as a laminate of molybdenum (Mo) and antimony(Sb) layers using gases selected from one or more of argon (Ar), oxygen(O₂), or nitrogen (N₂). In an embodiment, the alloy of the absorberlayer in some embodiments is deposited layer by layer as a laminate ofmolybdenum (Mo) and antimony (Sb) layers using a mixture of argon andoxygen gases (Ar+O₂). In some embodiments, layer by layer depositionusing a mixture of argon and oxygen gases (Ar+O₂) forms an oxide ofmolybdenum (Mo) and/or an oxide of antimony (Sb) for an alloy ofmolybdenum (Mo) and antimony (Sb). In other embodiments, layer by layerdeposition using a mixture of argon and oxygen gases (Ar+O₂) does notform an oxide of the metals that make up these laminates. In anembodiment, the alloy of the absorber layer in some embodiments isdeposited layer by layer as a laminate of molybdenum (Mo) and antimony(Sb) layers for an alloy of molybdenum (Mo) and antimony (Sb) using amixture of argon and nitrogen gases (Ar+N₂). In some embodiments, layerby layer deposition using a mixture of argon and nitrogen gases (Ar+N₂)forms a nitride of molybdenum (Mo) and/or a nitride of antimony (Sb) foran alloy of molybdenum (Mo) and antimony (Sb). In other embodiments,layer by layer deposition using a mixture of argon and nitrogen gases(Ar+N₂) does not form a nitride of the metals that make up each of theselaminates. In an embodiment, the alloy of the absorber layer in someembodiments is deposited layer by layer as a laminate of molybdenum (Mo)and antimony (Sb) layers for an alloy of molybdenum (Mo) and antimony(Sb) using a mixture of argon and oxygen and nitrogen gases (Ar+O₂+N₂).In some embodiments, layer by layer depositing using a mixture of argonand oxygen and nitrogen gases (Ar+O₂+N₂) forms an oxide and/or nitrideof molybdenum (Mo) and/or an oxide and/or nitride of antimony (Sb) foran alloy of molybdenum (Mo) and antimony (Sb). In other embodiments,layer by layer deposition using a mixture of argon and oxygen andnitrogen gases (Ar+O₂+N₂) does not form an oxide or a nitride of one ormore components of these laminates.

In one or more embodiments, bulk targets of the alloy compositionsdescribed herein may be made by normal sputtering using gases selectedfrom one or more of argon (Ar), oxygen (O₂), or nitrogen (N₂). In one ormore embodiments, the alloy is deposited using a bulk target having thesame composition of the alloy and is sputtered using a gas selected fromone or more of argon (Ar), oxygen (O₂), or nitrogen (N₂) to form theabsorber layer. In an embodiment, the alloy of the absorber layer insome embodiments is deposited using a bulk target having the samecomposition of the alloy and is sputtered using a mixture of argon andoxygen gases (Ar+O₂). In some embodiments, bulk target deposition usinga mixture of argon and oxygen gases (Ar+O₂) forms an oxide of molybdenum(Mo) and/or an oxide of antimony (Sb) for an alloy of molybdenum (Mo)and antimony (Sb). In other embodiments, bulk target deposition using amixture of argon and oxygen gases (Ar+O₂) does not form an oxide of eachof the metals of these laminates. In an embodiment, the alloy of theabsorber layer in some embodiments is deposited using a bulk targethaving the same composition of the alloy and is sputtered using amixture of argon and nitrogen gases (Ar+N₂). In some embodiments, bulktarget deposition using a mixture of argon and nitrogen gases (Ar+N₂)forms a nitride of molybdenum (Mo) and/or a nitride of antimony (Sb) foran alloy of molybdenum (Mo) and antimony (Sb). In other embodiments,bulk target deposition using a mixture of argon and nitrogen gases(Ar+N₂) does not form a nitride of one or more of the components of thealloys. In an embodiment, the alloy of the absorber layer in someembodiments is deposited using a bulk target having the same compositionof the alloy and is sputtered using a mixture of argon and oxygen andnitrogen gases (Ar+O₂+N₂). In some embodiments, bulk target depositingusing a mixture of argon and oxygen and nitrogen gases (Ar+O₂+N₂) formsan oxide and/or nitride of molybdenum (Mo) and/or an oxide and/ornitride of antimony (Sb) for an alloy of molybdenum (Mo) and antimony(Sb). In other embodiments, bulk target deposition using a mixture ofargon and oxygen and nitrogen gases (Ar+O₂+N₂) does not form an oxide ora nitride of one or more components of the alloy. In some embodiments,the alloy of molybdenum (Mo) and antimony (Sb) is doped with one of moreof nitrogen (N) or oxygen (O) in a range of from 0.1 wt. % to 5 wt. %.

The EUV mask blank in some embodiments is made in a physical depositionchamber having a first cathode comprising a first absorber material, asecond cathode comprising a second absorber material, a third cathodecomprising a third absorber material, a fourth cathode comprising afourth absorber material, and a fifth cathode comprising a fifthabsorber material, wherein the first absorber material, second absorbermaterial, third absorber material, fourth absorber material and fifthabsorber materials are different from each other, and each of theabsorber materials have an extinction coefficient that is different fromthe other materials, and each of the absorber materials have an index ofrefraction that is different from the other absorber materials.

Referring now to FIG. 5, an extreme ultraviolet mask blank 400 is shownas comprising a substrate 414, a multilayer stack of reflective layers412 on the substrate 414, the multilayer stack of reflective layers 412including a plurality of reflective layer pairs. In one or moreembodiments, the plurality of reflective layer pairs are made from amaterial selected from a molybdenum (Mo) containing material and silicon(Si) containing material. In some embodiments, the plurality ofreflective layer pairs comprises alternating layers of molybdenum (Mo)and silicon (Si). The extreme ultraviolet mask blank 400 furtherincludes a capping layer 422 on the multilayer stack of reflectivelayers 412, and there is a multilayer stack 420 of absorber layers onthe capping layer 422. In one or more embodiment, the plurality ofreflective layers 412 are selected from a molybdenum (Mo) containingmaterial and a silicon (Si) containing material and the capping layer422 comprises ruthenium (Ru).

The multilayer stack 420 of absorber layers including a plurality ofabsorber layer pairs 420 a, 420 b, 420 c, 420 d, 420 e, 420 f, each pair(420 a/420 b, 420 c/420 d, 420 e/420 f) each comprising an alloy ofmolybdenum (Mo) and antimony (Sb). In one example, absorber layer 420 ais made from molybdenum (Mo) and the material that forms absorber layer420 b is antimony (Sb). Likewise, absorber layer 420 c is made frommolybdenum (Mo) and the material that forms absorber layer 420 d isantimony (Sb), and absorber layer 420 e is made from molybdenum (Mo)material and the material that forms absorber layer 420 f is antimony(Sb).

In an embodiment, the absorber layer 310 is made from an alloy ofmolybdenum (Mo) and antimony (Sb). In one or more embodiments, theabsorber layer comprises an alloy of molybdenum (Mo) and antimony (Sb),and the alloy comprises from about 3.9 wt. % to about 93.8 wt. %molybdenum (Mo) and from about 6.2 wt. % to about 96.1 wt. % antimony(Sb) based upon the total weight of the alloy. In one or moreembodiments, the alloy comprises from about 13.9 wt. % to about 93.8 wt.% molybdenum (Mo) and from about 6.2 wt. % to about 86.1 wt. % antimony(Sb) based upon the total weight of the alloy. In one or moreembodiments, the alloy comprises from about 23.9 wt. % to about 93.8 wt.% molybdenum (Mo) and from about 6.2 wt. % to about 76.1 wt. % antimony(Sb) based upon the total weight of the alloy. In one or moreembodiments, the alloy comprises from about 33.9 wt. % to about 93.8 wt.% molybdenum (Mo) and from about 6.2 wt. % to about 66.1 wt. % antimony(Sb) based upon the total weight of the alloy. In one or moreembodiments, the alloy of molybdenum (Mo) and antimony (Sb) is asingle-phase alloy.

According to one or more embodiments, the absorber layer pairs comprisea first layer (420 a, 420 c, 420 e) and a second absorber layer (420 b,420 d, 420 f) each of the first absorber layers (420 a, 420 c, 420 e)and second absorber layer (420 b, 420 d, 420 f) have a thickness in arange of 0.1 nm and 10 nm, for example in a range of 1 nm and 5 nm, orin a range of 1 nm and 3 nm. In one or more specific embodiments, thethickness of the first layer 420 a is 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm,0.9 nm, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm,1.8 nm, 1.9 nm, 2 nm, 2.1 nm, 2.2 nm, 2.3 nm, 2.4 nm, 2.5 nm, 2.6 nm,2.7 nm, 2.8 nm, 2.9 nm, 3 nm, 3.1 nm, 3.2 nm, 3.3 nm, 3.4 nm, 3.5 nm,3.6 nm, 3.7 nm, 3.8 nm, 3.9 nm, 4 nm, 4.1 nm, 4.2 nm, 4.3 nm, 4.4 nm,4.5 nm, 4.6 nm, 4.7 nm, 4.8 nm, 4.9 nm, and 5 nm. In one or moreembodiments, the thickness of the first absorber layer and secondabsorber layer of each pair is the same or different. For example, thefirst absorber layer and second absorber layer have a thickness suchthat there is a ratio of the first absorber layer thickness to secondabsorber layer thickness of 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1,4.5:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1,16:1, 17:1, 18:1, 19:1, or 20:1, which results in the first absorberlayer having a thickness that is equal to or greater than the secondabsorber layer thickness in each pair. Alternatively, the first absorberlayer and second absorber layer have a thickness such that there is aratio of the second absorber layer thickness to first absorber layerthickness of 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 6:1, 7:1,8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or20:1 which results in the second absorber layer having a thickness thatis equal to or greater than the first absorber layer thickness in eachpair.

According to one or more embodiments, the different absorber materialsand thickness of the absorber layers are selected so that extremeultraviolet light is absorbed due to absorbance and due to a phasechange caused by destructive interference with light from the multilayerstack of reflective layers. While the embodiment shown in FIG. 5 showsthree absorber layer pairs, 420 a/420 b, 420 c/420 d and 420 e/420 f,the claims should not be limited to a particular number of absorberlayer pairs. According to one or more embodiments, the EUV mask blank400 in some embodiments includes in a range of 5 and 60 absorber layerpairs or in a range of 10 and 40 absorber layer pairs.

According to one or more embodiments, the absorber layers have athickness which provides less than 2% reflectivity and other etchproperties. A supply gas in some embodiments is used to further modifythe material properties of the absorber layers, for example, nitrogen(N₂) gas in some embodiments is used to form nitrides of the materialsprovided above. The multilayer stack of absorber layers according to oneor more embodiments is a repetitive pattern of individual thickness ofdifferent materials so that the EUV light not only gets absorbed due toabsorbance but by the phase change caused by multilayer absorber stack,which will destructively interfere with light from multilayer stack ofreflective materials beneath to provide better contrast.

Another aspect of the disclosure pertains to a method of manufacturingan extreme ultraviolet (EUV) mask blank comprising forming on asubstrate, a multilayer stack of reflective layers on the substrate, themultilayer stack including a plurality of reflective layer pairs,forming a capping layer on the multilayer stack of reflective layers,and forming absorber layer on the capping layer, the absorber layercomprising an alloy of molybdenum (Mo) and antimony (Sb).

Another aspect of the disclosure pertains to an extreme ultraviolet(EUV) mask blank comprising a substrate, a multilayer stack whichreflects EUV radiation, the multilayer stack including a plurality ofreflective layer pairs including molybdenum (Mo) and silicon (Si), acapping layer on the multilayer stack of reflecting layers, and anabsorber layer comprising an alloy of molybdenum (Mo) and antimony (Sb),the alloy of molybdenum (Mo) and antimony (Sb) comprising from about33.9 wt. % to about 90.0 wt. % molybdenum (Mo) and from about 10.0 wt. %to about 66.1 wt. % antimony (Sb) based upon the total weight of thealloy.

The EUV mask blank in some embodiments has any of the characteristics ofthe embodiments described above with respect to FIG. 4 and FIG. 5, andthe method in some embodiments is performed in the system described withrespect to FIG. 3.

Thus, in an embodiment, the plurality of reflective layers are selectedfrom molybdenum (Mo) containing material and silicon (Si) containingmaterial and the absorber layer comprises an alloy of molybdenum (Mo)and antimony (Sb).

In another specific method embodiment, the different absorber layers areformed in a physical deposition chamber having a first cathodecomprising a first absorber material and a second cathode comprising asecond absorber material. Referring now to FIG. 6 an upper portion of amulti-cathode chamber 500 is shown in accordance with an embodiment. Themulti-cathode chamber 500 includes a base structure 501 with acylindrical body portion 502 capped by a top adapter 504. The topadapter 504 has provisions for a number of cathode sources, such ascathode sources 506, 508, 510, 512, and 514, positioned around the topadapter 504.

In one or more embodiments, the method forms an absorber layer that hasa thickness in a range of 5 nm and 60 nm. In one or more embodiments,the absorber layer has a thickness in a range of 51 nm and 57 nm. In oneor more embodiments, the materials used to form the absorber layer areselected to effect etch properties of the absorber layer. In one or moreembodiments, the alloy of the absorber layer is formed by co-sputteringan alloy absorber material formed in a physical deposition chamber,which in some embodiments provides much thinner absorber layer thicknessthan a TaN absorber layer and achieving less than 2% reflectivity anddesired etch properties. In an embodiment, the etch properties and otherdesired properties of the absorber layer in some embodiments aretailored to specification by controlling the alloy percentage of eachabsorber material. In an embodiment, the alloy percentage in someembodiments is precisely controlled by operating parameters suchvoltage, pressure, flow etc., of the physical vapor deposition chamber.In an embodiment, a process gas is used to further modify the materialproperties, for example, nitrogen (N₂) gas is used to form nitrides ofmolybdenum (Mo) and/or nitrides of antimony (Sb) for an alloy molybdenum(Mo) and antimony (Sb).

The multi-cathode source chamber 500 in some embodiments is part of thesystem shown in FIG. 3. In an embodiment, an extreme ultraviolet (EUV)mask blank production system comprises a substrate handling vacuumchamber for creating a vacuum, a substrate handling platform, in thevacuum, for transporting a substrate loaded in the substrate handlingvacuum chamber, and multiple sub-chambers, accessed by the substratehandling platform, for forming an EUV mask blank, including a multilayerstack of reflective layers on the substrate, the multilayer stackincluding a plurality of reflective layer pairs, a capping layer on themultilayer stack of reflective layers, and an absorber layer on thecapping layer, the absorber layer comprising an alloy of molybdenum (Mo)and antimony (Sb). The system in some embodiments is used to make theEUV mask blanks shown with respect to FIG. 4 or FIG. 5 and have any ofthe properties described with respect to the EUV mask blanks describedwith respect to FIG. 4 or FIG. 5 above.

Processes may generally be stored in the memory as a software routinethat, when executed by the processor, causes the process chamber toperform processes of the present disclosure. The software routine mayalso be stored and/or executed by a second processor (not shown) that isremotely located from the hardware being controlled by the processor.Some or all of the method of the present disclosure may also beperformed in hardware. As such, the process may be implemented insoftware and executed using a computer system, in hardware as, e.g., anapplication specific integrated circuit or other type of hardwareimplementation, or as a combination of software and hardware. Thesoftware routine, when executed by the processor, transforms a generalpurpose computer into a specific purpose computer (controller) thatcontrols the chamber operation such that the processes are performed.

Reference throughout this specification to “one embodiment,” “certainembodiments,” “one or more embodiments” or “an embodiment” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. Thus, the appearances of the phrases such as “in one ormore embodiments,” “in certain embodiments,” “in one embodiment” or “inan embodiment” in various places throughout this specification are notnecessarily referring to the same embodiment of the disclosure.Furthermore, the particular features, structures, materials, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

Although the disclosure herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent disclosure. It will be apparent to those skilled in the art thatvarious modifications and variations can be made to the method andapparatus of the present disclosure without departing from the spiritand scope of the disclosure. Thus, it is intended that the presentdisclosure include modifications and variations that are within thescope of the appended claims and their equivalents.

What is claimed is:
 1. A method of manufacturing an extreme ultraviolet(EUV) mask blank comprising: forming on a substrate a multilayer stackwhich reflects EUV radiation, the multilayer stack comprising aplurality of reflective layer pairs; forming a capping layer on themultilayer stack; and forming an absorber layer on the capping layer,the absorber layer comprising an alloy of molybdenum (Mo) and antimony(Sb).
 2. The method of claim 1, wherein the alloy of molybdenum (Mo) andantimony (Sb) comprises from about 3.9 wt. % to about 93.8 wt. %molybdenum (Mo) and from about 6.2 wt. % to about 96.1 wt. % antimony(Sb).
 3. The method of claim 1, wherein the alloy of molybdenum (Mo) andantimony (Sb) comprises from about 13.9 wt. % to about 93.8 wt. %molybdenum (Mo) and from about 6.2 wt. % to about 86.1 wt. % antimony(Sb).
 4. The method of claim 1, wherein the alloy of molybdenum (Mo) andantimony (Sb) comprises from about 23.9 wt. % to about 93.8 wt. %molybdenum (Mo) and from about 6.2 wt. % to about 76.1 wt. % antimony(Sb).
 5. The method of claim 1, wherein the alloy of molybdenum (Mo) andantimony (Sb) comprises from about 33.9 wt. % to about 93.8 wt. %molybdenum (Mo) and from about 6.2 wt. % to about 66.1 wt. % antimony(Sb).
 6. The method of claim 1, wherein the alloy of molybdenum (Mo) andantimony (Sb) is amorphous.
 7. The method of claim 2, wherein the alloyof molybdenum (Mo) and antimony (Sb) is formed by co-sputtering separatemolybdenum (Mo) and antimony (Sb) targets with a gas selected from oneor more of argon (Ar), oxygen (O₂), or nitrogen (N₂) to form theabsorber layer.
 8. The method of claim 1, wherein the alloy is depositedlayer by layer as a laminate of alternate molybdenum (Mo) and antimony(Sb) layers using a gas selected from one or more of argon (Ar), oxygen(O₂), or nitrogen (N₂) to form the absorber layer.
 9. The method ofclaim 1, wherein the alloy of molybdenum (Mo) and antimony (Sb) isdeposited using a bulk target having a same composition as the alloy andis sputtered using a gas selected from one or more of argon (Ar), oxygen(O₂), or nitrogen (N₂) to form the absorber layer.
 10. The method ofclaim 1, wherein the alloy of molybdenum (Mo) and antimony (Sb) is dopedwith one of more of nitrogen (N) or oxygen (O) in a range of from 0.1wt. % to 5 wt. %.
 11. An extreme ultraviolet (EUV) mask blankcomprising: a substrate; a multilayer stack which reflects EUVradiation, the multilayer stack comprising a plurality of reflectivelayer pairs; a capping layer on the multilayer stack of reflectinglayers; and an absorber layer comprising an alloy of molybdenum (Mo) andantimony (Sb).
 12. The extreme ultraviolet (EUV) mask blank of claim 11,wherein the alloy of molybdenum (Mo) and antimony (Sb) comprises fromabout 3.9 wt. % to about 93.8 wt. % molybdenum (Mo) and from about 6.2wt. % to about 96.1 wt. % antimony (Sb).
 13. The extreme ultraviolet(EUV) mask blank of claim 11, wherein the alloy of molybdenum (Mo) andantimony (Sb) comprises from about 13.9 wt. % to about 93.8 wt. %molybdenum (Mo) and from about 6.2 wt. % to about 86.1 wt. % antimony(Sb).
 14. The extreme ultraviolet (EUV) mask blank of claim 11, whereinthe alloy of molybdenum (Mo) and antimony (Sb) comprises from about 23.9wt. % to about 93.8 wt. % molybdenum (Mo) and from about 6.2 wt. % toabout 76.1 wt. % antimony (Sb).
 15. The method of claim 11, wherein thealloy of molybdenum (Mo) and antimony (Sb) comprises from about 33.9 wt.% to about 93.8 wt. % molybdenum (Mo) and from about 6.2 wt. % to about66.1 wt. % antimony (Sb).
 16. The extreme ultraviolet (EUV) mask blankof claim 11, wherein the alloy of molybdenum (Mo) and antimony (Sb) isamorphous.
 17. The extreme ultraviolet (EUV) mask blank of claim 11,wherein the absorber layer has a thickness of less than 60 nm.
 18. Theextreme ultraviolet (EUV) mask blank of claim 11, wherein the absorberlayer further comprises a range of from about 0.1 wt. % to about 5 wt. %of a dopant selected from one or more of nitrogen (N) or oxygen (O). 19.The extreme ultraviolet (EUV) mask blank of claim 17, wherein theabsorber layer has a thickness of less than 60 nm.
 20. An extremeultraviolet (EUV) mask blank comprising: a substrate; a multilayer stackwhich reflects EUV radiation, the multilayer stack comprising aplurality of reflective layer pairs including molybdenum (Mo) andsilicon (Si); a capping layer on the multilayer stack of reflectinglayers; and an absorber layer comprising an alloy of molybdenum (Mo) andantimony (Sb), wherein the alloy of molybdenum (Mo) and antimony (Sb)comprises from about 33.9 wt. % to about 90.0 wt. % molybdenum (Mo) andfrom about 10.0 wt. % to about 66.1 wt. % antimony (Sb).